Inking and dampening apparatus for printing press



A ril 25, 1961 R. J. cRlssY 2,981,180

INKING AND DAMPENING APPARATUS FOR PRINTING PRESS ATTORNEY United States Patent 6 INKING AND DAMPENIN G APPARATUS FOR- PRINTING PRESS This invention relates to rotary printing presses and more particularly to a method and apparatus for inking and dampening a lithographic printing plate mounted on such a press.

In lithographic printing, which is dependent upon the well known principle that grease and water are immiscible, a printing plate is provided with an ink-receptive image, the plate is then dampened with an ink repellent soultion which, of course, affects only the non-image portion of the plate, the image being greasy hence waterrepellent, and the plate is then inked, the ink adhering only to the image since the remainder of the plate has been dampened to repel ink. The image is then either reproduced directly onto sheets fed into the printing couple, or it is offset first onto a rubber blanket which then prints the sheets. The printing plate is then reinked and re-dampened and the printing operation is repeated.

In order to perform the abovementioned inking and dampening operations, lithographic machines are usually provided with two systems of rollers, one for dampening the plate and the other for inking it. Conventionally, one or more rollers of each system are brought into contact with the printing plate on each cycle of the machine, and these rollers are lifted out of contact with the plate cylinder when that portion of the cylinder which is not occupied by the printing plate passes beneath them. Although the method of dampening described is widely used, there are certain important disadvantages associated with it which often render the quality of reproduction imperfect. For one thing, the entire amount of ink which is applied to the image on the plate is not utilized when a sheet is printed, but rather, much of the ink remains on the plate after each cycle. Therefore, when the dampening form roller contacts the plate during the following cycle, it may disturb some of the excess ink thus leaving the image ragged. In addition, the dampening roller picks up some of the excess ink thereby introducing it into the dampening system which eventually results in giving the printed sheets an over-all grey tone appearance. Furthermore, inasmuch as the dampening form rolleris ordinarily covered with a cotton fabric of one sort or another, it has a tendency to deposit lint on the printing plate during its contact therewith. The lint, naturally, forms ink repellent bridges over portions of the image, thus making it impossible for the image to be completely reproduced.

It is the object of the present invention to alleviate the above described difificulties by transmitting the dampening solution to the lithographic plate via the same rollers which ink the plate, thereby eliminating the requirement that the dampening rollers contact the plate. Employing the ink form rollers to dampen the plate is not a method which does not present difiiculties of its own, however, such as for example, the problem of maintaining the inkdampener balance originally prescribed, or in other words, the problem of keeping ink out of the dampening system and dampener out of the inking system. The present disclosure does, however, solve these difiiculties by employing an intermediate surface, upon which a film of dampening solution is intermittently distributed, to transmit the dampening solution to the ink form rollers, so that no part of the dampening system need engage any inking 2,981,180 Patented Apr. 25, 1961 ice 2 roller. The ink form roller then applies both dampener and ink to the printing plate. In this way, the dampen-v ing rollers are kept out of contact with both the inking rollers and the inkedimage on the plate.

Another object of the present invention is to reduce costs in manufacturing and maintenance of the printing press by eliminating the familiar dampening distributor roller and dampening form roller. Furthermore, it has been found that when the present method is employed, the static electricity, which is generated during the printing operation and which greatly interferes with proper delivery of the printed sheets, is substantially reduced or eliminated.

Other objects and advantages of the present invention will be apparent from the following description which is made with reference to the accompanying drawings.

In the drawings:

Fig. l is a schematic elevational view of a three-cylinder printing press with the present invention applied thereto;

Figs. 2 and 3 are schematic elevational views of a twocylinder printing press having the present invention applied, thereto, and showing the plate-platen cylinder in two positions;

Fig. 4 is a schematic elevational view of a two-cylinder printing press with the present invention applied thereto;

Fig. 5 is a cross-sectional view taken on line 5-5 of Fig. 3; and

Fig. 6 is a partial schematic elevation view of an alternative embodiment of the present invention.

The conventional two-cylinder printing press 10 of- Fig. 2 comprises a plate-platen cylinder 11, having a. plate segment 12 and an impression or balance segment 13, and a blanket cylinder 14. A lithographic printing; plate 15, bearing the image to be reproduced, is mounted, on the plate segment 12. and it is preferred that a blank printing plate 18 be mounted on the balance segment 13-. The printing plate 15 must, of course, be dampened and inked during each cycle of the press and this is accom plished by the usual dampening system 19 and inking system 20. As is well known, the inking system 20.

comprises a large number of rollers, of which only a few, the distributor roller 21 and two form rollers 22, are shown, in order to properly break up the ink so that it may be applied evenly to the plate 15. The dampening system comprises a fountain 23 containing the dampener, a fountain roller 26 which rotates in the fountain and becomes charged with dampener, a transfer roller 27 which is oscillated by the cam 28 and transmits dampener from the fountain roller 26 to the distributor roller 29, and a form roller 30 which picks up dampener from they distributor roller 29 and ordinarily applies it to the plate.

15. It follows, therefore, that ordinarily both the ink and dampener form rollers contact the plate segment 12, causing the ill eifects mentioned above, and are cammed out of engagement with the balance segment 13. Accord ing to the present invention, however, the dampening form roller contacts the balance segment 13 but is, cammed out of engagement with the plate segment 12 by a cam 31, which extends along the peripheral length, of the segment 12, and cooperates with a follower 34' mounted adjacent the end of form roller 30 (see Fig. 5).,

On the other hand, the ink form rollers are provided; with no such followers and hence contact both the plate-- segment '12 and the balance'segment 13 (see Figs. 2

and 3).

In operation, the form roller 31 applies a suflicient' amount of dampening solution to the blank plate 18:,

mounted on the balance segment 13. As the cylinderll continues to rotate, roller 30 is lifted by the cam 31 in; order to prevent the roller from contacting the inked image on plate 15. When the ink form rollers 22, contact the 3 dampened plate 18, which occurs after they have been replenished with ink by the distributor roller 21, the film of dampener which has been distributed over the plate 18 is picked up by the rollers 22. Thereafter, when the ink form rollers engage the printing plate 15, the dampening.

directly, but rather as an intermittently predistributed' film on an intermediate surface, whereas the ink is constantly fed from the ink fountain to the ink form rollers, there is substantially no opportunity for any dampening solution to infiltrate the inking system, hence the efficiency ofthe inking system will not be impaired and the inkdampener balance originally prescribed will be maintained. Note also, that the present invention may be utilized with a presently commercially available machine after only slight adjustment thereof.

As may be seen in Fig. 1, the present invention is applicable to three-cylinder presses as well as two-cylinder presses. The only modification which should be made is in the positioning of the inking system 20 and the dampening system 19, whose positions are exchanged with reference to their positions in Fig. 2, due to the reverse rotation of the plate cylinder 35 as compared with the plateplaten cylinder 11. The balance segment 36 of cylinder 35 is preferably provided with a blank printing plate 37 upon which a film of dampening solution is applied by the dampening form roller 30 which solution is then picked up by the inking form rollers 22, and applied to the printing plate 38 simultaneously with the ink. It goes without saying that the blank printing plate 37 may merely be a blank portion of the printing plate 38. The cam 39 which extends around the peripheral length of the image segment of the plate cylinder 35, prevents the dampener form roller 30 from contacting the inked image on'the plate.

As is well known, the two-cylinder printing press of Fig. 4 may be equipped to print both sides of a sheet, passing between the printing couple, at the same time. To do this, a direct lithographic plate 42 is mounted on the plate segment 12, for example, and an offset lithographic plate 43 is mounted on the balance segment. Ordinarily then, since both plates must be inked and dampened before printing may be accomplished, the inking and dampening form rollers 22 and 30 contact both printing plates. When the present invention is applied to such a press, however, the dampening form roller need contact only one of the printing plates such as, for example, plate 43, thus substantially reducing the attendant ill effects produced when the roller 30 contacts both printing plates.

As mentioned before, the present invention permits the conventional dampening distributor roller 29 and dampening form roller 30 to be eliminated, thus saving both manufacturing and maintenance costs on future machines employing this method. Referring to Fig. 6, the

dampening fountain .23 with its roller 26, and the transfer roller 27 with its associated mechanism, are moved closer to the plate cylinder 11 to a position wherein the transfer roller 27 may shuttle between the fountain roller 26 and the balance or non-image segment of the press, thus providing the same effect as is provided by the above described form roller. This is possible since the balance segment takes the place of the distributor roller 29, and.

the ink form rollers 22 take the place of the dampening form roller 30. The cam 28 is, of course, properly timed to lift the roller 27 into contact with the roller 26 when the printing image is passing therebeneath, and to 4 permit the roller 27 to distribute the dampener thus acquired to blank plate, thus eliminating theneed for a cam such as cam 31 of Fig. 2.

Finally, it should be noted that the manner in which the dampening solution is applied to the balance or nonimage portion of the plate cylinder, e.g., by means of a roller, as described above, by means of a spray, or by means of condensation, etc., is not important to the method of the present invention, although it is preferred that roller means be employed.

The invention has been shown and described in preferred form only and by way of example, and many variations and modifications may be made therein and in its mode of application which will still be comprised within its spirit. It is understood, therefore, that the invention is not limited to any specific form or embodiment, except insofar as such limitations are specified in the appended claims.

What is claimed is:

1. In a lithographic printing press having a cylinder provided with a printing segment and a non-ink receptive non-printing segment, means for dampening said nonprinting segment only, and an inking member which subsequently contacts both the thus pre-dampened nonprinting segment and said printing segment, whereby ink and water are simultaneously applied to said printing 7 7 segment.

2. In a lithographic printing press having a cylinder provided with a printing segment and a non-ink receptive non-printing segment, a dampening roller adapted to contact said non-printing segment only, and an inking member adapted to contact both the printing segment and the non-printing segment of said cylinder, whereby ink and water are simultaneously applied to said printing segment.

3. In a lithographic printing press having a cylinder provided with a printing segment and a non-ink receptive non-printing segment, a dampening roller adapted to contact the non-printing segment only of said cylinder, means for camming said roller out of contact with the printing segment of said cylinder, and an inking member adapted to contact both the printing segment and the non-printing segment of said cylinder.

4. In a lithographic printing press having a cylinder provided with a printing segment and a non-ink receptive non-printing segment, a roller adapted to contact the non-printing segment only of said cylinder for dampening that segment, said roller being provided with a cam follower, a cam disposed along the peripheral length of said printing segment to engage said follower and maintain said roller out of contact with said printing segment, and an inking member adapted to contact both the printing segment and the non-printing segment of said cylinder.

5. In a lithographic printing press having a cylinder provided with a printing segment and a non-ink receptive non-printing segment, a dampening fountain, a fountain roller disposed in said fountain, and a transfer roller adapted to oscillate periodically between said fountain roller and said non-printing segment to dampen said non-printing segment, said periods being so timed that said transfer roller never contacts the printing segment of said cylinder, and an inking member adapted to contact both the printing segment and the non-printing segment of said cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 362,320 Scherber May 3, 1887 664,965 Morriss Ian. 1, 1901 683,478 Meyer Oct. 1, 1901 1,120,770 Wagner et al. Dec. 15, 1914 2,103,254 Goedike Dec. 28, 1937 2,270,273 Davidson Jan. 20, 1942 "2,678,001 7 Davidson May 11, 1954' 

